Hi,
I did recently face the same issue.
Opera is quite unstable (v. 48 on High Sierra 10.13)
I cannot add a bookmark or create a folder in the bookmarks bar. It crashes every time.
Moreover, when Opera is in the fullscreen mode I cannot create a new (private) window.
In the previous version I could not use the trackpad gestures to zoom in or out.
It became so buggy, and some issue affects basics functionality of the opera and are critical (crashes) that I started to doubt about their functional tests suite.
I really like Opera browser, but for me performance and stability of the product is very important, so I thing I will be going back using chrome.
jtonic